Technical Field
The present disclosure relates to an apparatus for testing the integrity of mammary tissues.
In particular, the disclosure relates to an apparatus which allows the detection of breast tumours and the test by means of imaging of the integrity of portions of the body.
Description of the Related Art
As it is well known, in medical applications methods of analysis based on imaging are considered of great interest.
The known methods provide tomographic reconstructions of tissues using different means:                ultrasound scanners;        X-ray based computed tomography (CT);        nuclear magnetic resonance imaging (MRI)        
Such methods are affected by multiple problems.                ultrasound is subject to problems of contrast and inability to detect images of objects with high differences in terms of acoustic impedance, such as in areas with air and bone;        tomography entails administering doses of ionizing radiation to the patient;        magnetic resonance requires lengthy periods of application of the magnetic field and is very costly.        
Moreover, in the specific application of breast cancer detection, the limitations of X-ray mammography are well known.
More precisely, this technique, even with high-resolution images and with relatively low doses of radiation, fails to detect approximately 15% of cancers present, while approximately 75% of the identified breast lesions are, really, benign.
Over time, microwave imaging has attracted increasing attention, especially for its applicability in breast cancer detection; this is due to the significant contrast that is detected between normal and malign tissues, characteristic of the dielectric properties of the tissues at microwave frequencies.
Current research in microwave breast imaging can be divided into:                microwave tomography;        ultra-wide band (UWB) radio techniques.        
Unfortunately, these methods, too, are affected by multiple problems:                tomography is intrinsically unstable, since it requires solving a nonlinear inverse problem;        in UWB, complex focusing techniques are necessary; in some cases filters are necessary to improve the suppression of possible disturbing images (clutter suppression) and the spatial discrimination, but these entail an increase in complexity;        approaches based on time reversal (TR) techniques have also been proposed, but they require knowledge of the channel transfer function associated with the feedback.        
It should also be underlined that the proposed methods are characterized by a low S/C ratio.
In the literature of imaging analysis for breast cancer performed at microwave frequencies, the S/C ratio (Signal-to-Clutter ratio) within the breast area is assumed to be the ratio between the maximum response identifying a tumour and the maximum response identifying a possible image of disturbance (clutter) in the same image.
It may be deduced that the higher this ratio is, the better is the detection and determination of the position of possible non-integrities in the mammary tissue.
By way of example, in the previously mentioned technique which exploits focusing algorithms, the S/C ratio detected within the mammary tissue is 4 dB.
US patent application having publication number US 2006/0241409 discloses a microwave system for estimating the average dielectric properties of a breast tissue, in order to detect the presence and location of a tumour. This is achieved using an iterative method which is an extension of the time-domain inverse scattering algorithm based on a finite-difference time-domain method.
US patent application having publication number US 2011/0130656 discloses a microwave image reconstruction apparatus for the diagnosis of breast cancer. The apparatus comprises a plurality of antennas 190 1, #2, . . . #16 arranged in such a way as to permit insertion of a breast (see FIG. 2). The breast image reconstruction uses an iterative algorithm which comprises a log transformation of the amplitude values of the electromagnetic wave received from the plurality of antennas 190 1, #2, . . . #16, in order to improve the sensitivity and to reduce the number of performed calculations.